PAT Testing Terminology

The phrase 'PAT testing' is everywhere in the UK. It’s used by employers, contractors, training providers and test instrument manufacturers. But it’s worth understanding that PAT testing is an informal industry term, not the formal wording used by the IET Code of Practice.

What does the IET Code of Practice actually call it?

The Code of Practice has always described the process as in-service inspection and testing of electrical equipment. That wording matters because it highlights two key points: the work is not limited to “portable” appliances, and inspection is at least as important as testing.

It’s also worth noting that the phrase 'inspection and testing' is often used in relation to the fixed electrical installation, for example periodic inspection and testing (EICR). The Code of Practice avoids that confusion by being specific: it’s about in-service equipment (appliances and electrical equipment in use), not the building’s wiring system.

In simple terms, in-service inspection and testing typically includes:

• User checks (simple visual checks before use where appropriate)
• Formal visual inspections (more structured checks, often including plug wiring where a rewirable plug is fitted)
• Electrical tests (earth continuity, insulation resistance, leakage/touch current, polarity for leads, etc. where appropriate)

If you want the what’s included and what’s excluded overview, see our guide to what PAT testing covers (scope and exceptions).

Where does the term 'PAT' come from?

In practice, the term PAT appears to have originated from the test instrument used to carry out the electrical tests, rather than from the activity itself or from the equipment being inspected and tested. Early guidance in the 1st edition of the IET Code of Practice refers to the instrument as a portable appliance tester, noting that these testers are generally the most convenient way of providing the required test facilities.

That’s a subtle but important distinction: the word 'portable' describes the test instrument, not the equipment being tested. It means the instrument itself is portable and can be easily moved so inspection and testing can be carried out on-site, away from a bench or workshop environment.

Over time, using a portable appliance test instrument became known as 'PAT testing', and that label then spread to the whole activity. That’s how 'PAT testing' became the widely understood industry term, even though the Code of Practice uses the more accurate wording: in-service inspection and testing of electrical equipment.

"Generally portable appliance testers offer the most convenient means of supplying the required test facilities but this does not preclude the use of suitable individual general test instruments."

Why 'PAT testing' can be misleading

The downside of the phrase 'portable appliance testing' is that it can accidentally reinforce two common misunderstandings:

• It’s only portable appliances. In reality, the guidance can apply to a wide range of in-service equipment (including equipment connected via industrial plugs and some fixed or permanently connected equipment), provided it can be safely isolated where required.
• It’s mainly about electrical tests. In reality, many (often most) faults are found during the visual inspection, not by pressing a button on a tester.

If you want a practical example of how inspection and test selection work together, see our step-by-step guide on how to PAT test common appliances.

EET / Electrical Equipment Testing

You may have seen claims online that PAT has been officially replaced by a new term: EET or Electrical Equipment Testing. This is not the case.

The IET Code of Practice has not introduced 'EET' as a replacement term, and it does not use 'EET' terminology. The Code’s established wording remains in-service inspection and testing of electrical equipment.

As a term, 'electrical equipment testing' is also unhelpful because it puts the emphasis on testing. In real-world electrical safety management, inspection is fundamental: it identifies damage, overheating, poor plugs, poor strain relief, counterfeit or substandard items, misuse, and suitability issues that electrical tests alone may miss.

For a deeper explanation of the guidance framework used in the UK, see our article on the IET Code of Practice (5th Edition).

So what term should you use?

For most workplaces, it’s fine to use PAT testing because it’s widely understood. But when you’re writing policies, specifications, or explaining what you actually want a contractor to do, it’s often clearer to use wording like:

• In-service inspection and testing of electrical equipment (most accurate)
• Inspection and testing (PAT) (clear and still recognisable)

That wording helps keep the focus on doing the job properly: inspection first, then appropriate tests, with good records and clear defect control.

Frequently asked questions

If you want hands-on training that covers inspection technique, test selection, and interpreting readings properly, see our PAT testing courses.